Redundant systems including amateur radio communications
run by volunteer organizations such as
ARES.

Solar power electrical generation including solar power from
space.

Let us know what other areas should be covered!

Colored version of illustrations from the 1994 U.S. Army report
ADA278230,
Nuclear Environment Survivability. The mechanism is for a
400 km high altitude burst EMP: gamma rays hit the atmosphere between
20–40 km altitude, ejecting electrons which are then deflected sideways
by the earth’s magnetic field. This makes the electrons radiate EMP
over a massive area. Because of the curvature of earth’s magnetic field
over the USA, the maximum EMP occurs south of the detonation and the
minimum occurs to the north.